Sift or whisk flour, baking soda, and salt into a bowl.
With a handheld or standing mixer, beat together shortening and butter until smooth. Add 1½ cups sugar and continue beating until light and fluffy, about 5 minutes.
Add the eggs, 1 at a time, beating well after each addition. Add vanilla extract and beat until well combined. Add the flour mixture and blend until smooth.
Mix the 3 tbsp sugar with the ground cinnamon in a small bowl.
Roll the dough, by hand, into 1½-inch balls. Roll the balls in the cinnamon sugar and place evenly onto ungreased/unlined cookie sheets. Flatten the balls into ½-inch disks.
Bake until light brown, but still moist in the center, about 12 minutes. Cool on a rack.
Recipe by Bear In The Pantry at https://bearinthepantry.com/wp/snickerdoodle-cookies/